Volcano monitoring in lower Puna

Published April 28, 2013 - 12:05am

Special to West Hawaii Today

At the Hawaiian Volcano Observatory, we continuously strive to improve our capability to monitor the volcanoes we live on. We have made great improvements to our monitoring networks in recent years, both in instrumentation to measure seismicity, gas and deformation of the ground, and in the communications infrastructure that brings the data from these instruments to HVO for analysis.

We are particularly concerned with monitoring areas with dense populations atop and downslope of active rift zones, such as the lower east rift zone of Kilauea in lower Puna.

The lower Puna region has been a challenge to monitor instrumentally, the topography and dense vegetation make relaying the data via traditional radio links to the observatory difficult. Finding secure locations in this heavily populated area is another problem. A couple of weeks ago, we wrote in this column about the innovative and successful NetQuakes Initiative, in which homeowners volunteer to host a seismometer, allowing much more data to be collected for seismic monitoring and research.

While the seismic network in lower Puna has been modestly improved through new NetQuakes instrumentation, our deformation monitoring efforts in lower Puna have suffered serious blows recently due to theft and vandalism at key sites. Within the last year, two stations that housed borehole tiltmeters — instruments that very precisely measure the slope of the ground and transmit their data to the observatory in real time — were stripped of their solar panels, batteries and radio communication equipment. At one site, even the tiltmeter itself was lifted out of the ground and taken. This instrument would cost about $13,000 to replace, not including installation costs, but it’s hard to imagine that it’s worth more than the cost of scrap metal to the thieves.

The cost of the stolen materials is well over $40,000. The addition of our costs in planning, installing and trying to protect these sites raises the cost of the thefts to the taxpayers to at least $100,000. The thefts have been reported to Hawaii Police Department and the FBI.

More important than the monetary cost, however, is the gap left in our deformation monitoring network on the lower east rift zone. It’s clear that we can’t continue to maintain sites in isolated, unsupervised areas.

Inspired by your willingness to take part in the NetQuakes program, we again ask for your help. Instead of installing more tiltmeters, however, which are prohibitively expensive and would require drilling boreholes, we would like to find homes, actually yards, for GPS instruments. GPS is well-suited to monitor the subtle changes of the ground, as we can process the data at the observatory to track the position of the GPS antenna to within a centimeter, less than half an inch.

GPS instruments use satellites to accurately determine their position. Thus, the main requirement for a GPS installation is to have an unobstructed view of the sky. Clearly, full unobstructed views are unlikely in Puna; however; the instruments do need to be able to see the sky to at an angle of least 50 degrees down from straight overhead in most directions, and more in some directions. The site needs to be at least 30 feet from structures such as one-story houses and in an area that will remain undisturbed under normal circumstances. In order to get the data back to HVO, we would need either good cellphone reception or line-of-sight views to Mauna Kea or Puu Honuaula.

The whole setup fits within a 5-by-5-foot area with nothing higher than the 5-foot antenna. It would take about half a day to install, and we would need to service it about once a year.

If this sounds interesting and you would like to be part of the effort to monitor and contribute to research in understanding Kilauea Volcano, give HVO a call at 967-8804.

Kilauea activity update

A lava lake within the Halemaumau Overlook vent produced nighttime glow visible from the Jaggar Museum overlook and via HVO’s webcam during the past week. The lake level fluctuated, due to deflation-inflation cycles, and was generally 165 to 200 feet below the floor of Halemaumau.

On Kilauea’s east rift zone, breakouts from the Peace Day tube remain active above the pali and on the coastal plain. Small ocean entries are active on both sides of the Hawaii Volcanoes National Park boundary. The Kahaualea flow is no longer active, its front stalling about three miles northeast from Puu Oo.

There was one felt earthquake in the past week. At 2:21 a.m. Thursday, a magnitude-3.1 earthquake occurred four miles north of Mountain View at a depth of one mile.